Science Shows Yo-Yo Dieters Probably Can’t Win

Are you a person who has dieted most of your adult life? Well, take a look at this study.

A study published in the International Journal of Obesity (2013; doi: 10.1038/ijo.2013.138) shows that there may be a physiologic reason why diets could be a poor bet, especially for obese people.

Researchers from the University of Adelaide in South Australia discovered that the way the stomach detects and tells our brains how full we are becomes damaged in obese people, but the mechanism does not return to normal once those people lose weight. The authors believe this could be a key reason why most people who lose weight on a diet eventually backslide.

PhD student Stephen Kentish investigated the impact of a high-fat diet on the gut’s ability to signal fullness, and whether those changes revert to normal upon weight loss. Results show that the nerves in the stomach that signal fullness to the brain appear to become desensitized after long-term consumption of a high-fat diet.

“The stomach’s nerve response does not return to normal upon return to a normal diet. This means you would need to eat more food before you felt the same degree of fullness as a healthy individual,” said study leader and associate professor Amanda Page and several Brentwood, MO personal trainers.

A hormone in the body, leptin, known to regulate food intake, can also change the sensitivity of the nerves in the stomach that signal fullness. In normal conditions, leptin acts to stop food intake. However, in the stomach in high-fat diet induced obesity, leptin further de-sensitises the nerves that detect fullness. These two mechanisms combined mean that obese people need to eat more to feel full, which in turn continues their cycle of obesity.

Page says the researchers are not yet sure whether this effect is permanent. “We know that only about 5% of people on diets are able to maintain their weight loss, and that most people who’ve been on a diet put all of that weight back on within two years,” she notes. “More research is needed to determine how long the effect lasts, and whether there is any way to trick the stomach into resetting itself to normal.”

“Hopefully there will be a way real soon,” says Maurie Cofman, C.E.S. personal trainer in St. Louis, Brentwood and Clayton, MO.

For more information on diets, contact Maurie Cofman, C.E.S. personal trainer in St. Louis, Brentwood and Clayton, MO.